Non-bridging contact via structures in proximity

ABSTRACT

A first photoresist layer is patterned with a first pattern that includes an opening in a region between areas of two adjacent via holes to be formed. The opening in the first photoresist is transferred into a template layer to form a line trench therein. The lateral dimension of the trench is reduced by depositing a contiguous spacer layer that does not fill the trench completely. An etch-resistant material layer is conformally deposited and fills the trench, and is subsequently recessed to form an etch-resistant material portion filling the trench. A second photoresist layer is applied and patterned with a second pattern, which includes an opening that includes areas of two via holes and an area therebetween. A composite pattern of an intersection of the second pattern and the complement of the pattern of the etch-resistant material portion is transferred through the template layer.

BACKGROUND

The present disclosure relates to semiconductor processing methods, andparticularly to methods for low damage etch process for low dielectricconstant materials, and structures for effecting the same.

In a dense contact via hole array, the pitch of the contact via holes islimited by lithographic resolution. The smaller the distance between apair of contact via holes is, the greater the probability that aphysical pattern is bridged, either at a lithographic step or after apattern transfer etch. While multi-mask patterning schemes that employmultiple lithographic masks can alleviate bridging of contact via holesas printed in each developed photoresist layer, an adjacent pair ofcontact via holes is prone to bridging upon transfer of multiplelithographic patterns in the photoresist layers into an underlyinglayer. Thus, via hole bridging poses a severe limitation in scaling ofdimensions in a dense contact via hole array.

BRIEF SUMMARY

A pair of laterally spaced contact via holes is formed employing twolithographic masks and a self-aligned etch-resistant material portion. Afirst photoresist layer is patterned with a first pattern that includesan opening in a region between areas of two adjacent via holes to beformed. The opening in the first photoresist is transferred into atemplate layer to form a line trench therein. The lateral dimension ofthe trench is reduced by depositing a contiguous spacer layer that doesnot fill the trench completely. An etch-resistant material layer isconformally deposited and fills the trench, and is subsequently recessedto form an etch-resistant material portion filling the trench. A secondphotoresist layer is applied and patterned with a second pattern, whichincludes an opening that includes areas of two via holes and an areatherebetween. A composite pattern of an intersection of the secondpattern and the complement of the pattern of the etch-resistant materialportion is transferred through the template layer and through anunderlying layer in a subsequent pattern transfer etch.

According to an aspect of the present disclosure, a method of forming apatterned structure is provided, which includes: forming a line trenchhaving a first pattern in an upper portion of a template layer; forminga contiguous spacer layer within the line trench and over a top surfaceof the template layer; forming an etch-resistant material portion withinthe line trench and on sidewalls of the contiguous spacer layer; forminga patterned layer over the etch-resistant material portion and thetemplate layer, the patterned layer having a second pattern including anopening therein; and transferring a composite pattern of an intersectionof the second pattern and a complement of a pattern of theetch-resistant material portion into the template layer.

According to another aspect of the present disclosure, a structure isprovided, which includes: a stack of a template layer and a contiguousspacer layer; an etch-resistant material portion overlying a recessedportion of the stack; and a pair of via structures embedded within thestack and laterally spaced by the etch-resistant material portion andthe recessed portion of the stack.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a top-down view of a first exemplary structure afterapplication of a first photoresist layer according to a first embodimentof the present disclosure.

FIG. 1B is a vertical cross-sectional view of the first exemplarystructure of FIG. 1A.

FIG. 2A is a top-down view of the first exemplary structure afterpatterning the first photoresist layer with a first pattern according tothe first embodiment of the present disclosure.

FIG. 2B is a vertical cross-sectional view of the first exemplarystructure of FIG. 2A.

FIG. 3A is a top-down view of the first exemplary structure aftertransfer of the pattern in the first photoresist layer into a templatelayer according to the first embodiment of the present disclosure.

FIG. 3B is a vertical cross-sectional view of the first exemplarystructure of FIG. 3A.

FIG. 4A is a top-down view of the first exemplary structure afterformation of a contiguous spacer layer according to the first embodimentof the present disclosure.

FIG. 4B is a vertical cross-sectional view of the first exemplarystructure of FIG. 4A.

FIG. 5A is a top-down view of the first exemplary structure afterformation of an etch-resistant material layer according to the firstembodiment of the present disclosure.

FIG. 5B is a vertical cross-sectional view of the first exemplarystructure of FIG. 5A.

FIG. 6A is a top-down view of the first exemplary structure afterrecessing of the etch-resistant material layer to form an etch-resistantmaterial portion according to the first embodiment of the presentdisclosure.

FIG. 6B is a vertical cross-sectional view of the first exemplarystructure of FIG. 6A.

FIG. 7A is a top-down view of the first exemplary structure afterapplication of a second photoresist layer according to the firstembodiment of the present disclosure.

FIG. 7B is a vertical cross-sectional view of the first exemplarystructure of FIG. 7A.

FIG. 8A is a top-down view of the first exemplary structure afterpatterning the second photoresist layer, a second anti-reflectivecoating layer, and a second organic planarization layer with a secondpattern according to the first embodiment of the present disclosure.

FIG. 8B is a vertical cross-sectional view of the first exemplarystructure of FIG. 8A.

FIG. 9A is a top-down view of the first exemplary structure aftertransfer of a composite pattern of the intersection of the secondpattern and the complement of the pattern of the etch-resistant materialportion according to the first embodiment of the present disclosure.

FIG. 9B is a vertical cross-sectional view of the first exemplarystructure of FIG. 9A.

FIG. 10A is a top-down view of the first exemplary structure afterremoval of the second photoresist layer, the second ARC layer, and thesecond organic planarization layer according to the first embodiment ofthe present disclosure.

FIG. 10B is a vertical cross-sectional view of the first exemplarystructure of FIG. 10A.

FIG. 11A is a top-down view of the first exemplary structure afterformation of a pair of via structures according to the first embodimentof the present disclosure.

FIG. 11B is a vertical cross-sectional view of the first exemplarystructure of FIG. 11A.

FIG. 12A is a top-down view of a variation of the first exemplarystructure according to the first embodiment of the present disclosure.

FIG. 12B is a vertical cross-sectional view of the variation of thefirst exemplary structure of FIG. 12A.

FIG. 13A is a top-down view of a second exemplary structure according toa second embodiment of the present disclosure.

FIG. 13B is a vertical cross-sectional view of the second exemplarystructure of FIG. 13A.

FIG. 14A is a top-down view of a third exemplary structure aftertransfer of the pattern in the first photoresist layer into a templatelayer according to a third embodiment of the present disclosure.

FIG. 14B is a vertical cross-sectional view of the third exemplarystructure of FIG. 14A.

FIG. 15A is a top-down view of the third exemplary structure afterformation of a contiguous spacer layer according to the third embodimentof the present disclosure.

FIG. 15B is a vertical cross-sectional view of the third exemplarystructure of FIG. 15A.

FIG. 16A is a top-down view of the third exemplary structure afterformation of an etch-resistant material layer according to the thirdembodiment of the present disclosure.

FIG. 16B is a vertical cross-sectional view of the third exemplarystructure of FIG. 16A.

FIG. 17A is a top-down view of the third exemplary structure afterrecessing of the etch-resistant material layer to form an etch-resistantmaterial portion according to the third embodiment of the presentdisclosure.

FIG. 17B is a vertical cross-sectional view of the third exemplarystructure of FIG. 17A.

FIG. 18A is a top-down view of the third exemplary structure afterapplication of a third photoresist layer according to the thirdembodiment of the present disclosure.

FIG. 18B is a vertical cross-sectional view of the third exemplarystructure of FIG. 18A.

FIG. 19A is a top-down view of the third exemplary structure afterpatterning the third photoresist layer, a third anti-reflective coatinglayer, and a third organic planarization layer with a third patternaccording to the third embodiment of the present disclosure.

FIG. 19B is a vertical cross-sectional view of the third exemplarystructure of FIG. 19A.

FIG. 20A is a top-down view of the third exemplary structure aftertransfer of a composite pattern of the intersection of the third patternand the complement of the pattern of the etch-resistant material portionaccording to the third embodiment of the present disclosure.

FIG. 20B is a vertical cross-sectional view of the third exemplarystructure of FIG. 20A.

FIG. 21A is a top-down view of the third exemplary structure afterremoval of the third photoresist layer, the third ARC layer, and thethird organic planarization layer according to the third embodiment ofthe present disclosure.

FIG. 21B is a vertical cross-sectional view of the third exemplarystructure of FIG. 21A.

FIG. 22A is a top-down view of the third exemplary structure afterformation of a pair of via structures according to the third embodimentof the present disclosure.

FIG. 22B is a vertical cross-sectional view of the third exemplarystructure of FIG. 22A.

FIG. 23A is a top-down view of a variation of the third exemplarystructure according to the third embodiment of the present disclosure.

FIG. 23B is a vertical cross-sectional view of the variation of thethird exemplary structure of FIG. 23A.

FIG. 24A is a top-down view of a fourth exemplary structure according toa second embodiment of the present disclosure.

FIG. 24B is a vertical cross-sectional view of the fourth exemplarystructure of FIG. 24A.

DETAILED DESCRIPTION

As stated above, the present disclosure relates to methods for formingtrenches having different widths and the same depth, which are nowdescribed in detail with accompanying figures. Throughout the drawings,the same reference numerals or letters are used to designate like orequivalent elements. The drawings are not necessarily drawn to scale.

Referring to FIGS. 1A and 1B, a first exemplary structure according to afirst embodiment of the present disclosure includes a stack of asubstrate layer 10, at least one underlying material layer, a templatelayer 40, and at least one photosensitive-material-including layer. Theat least one underlying material layer can include, for example, adielectric material layer 30, an optional cap material layer 32, and anoptional hard mask layer 34. The at least onephotosensitive-material-including layer can include, for example, astack of a first organic planarization layer 42, a first antireflectivecoating (ARC) layer 44, and a first photoresist layer 47.

The dielectric material layer 30 includes a dielectric material that canbe employed for forming metal interconnect structures therein. Forexample, the dielectric material layer 30 can include undoped siliconoxide, doped silicon oxide, silicon nitride, silicon oxynitride,non-porous organosilicate glass (OSG), and porous OSG, or a combinationthereof. The dielectric material layer 30 can be formed, for example, bychemical vapor deposition (CVD) or spin-coating. The dielectric materiallayer 30 can have a thickness from 30 nm to 1,000 nm, although lesserand greater thicknesses can also be employed.

The optional cap material layer 32 can include a dielectric materialsuch as silicon oxide, silicon nitride, silicon oxynitride, a non-porousorganosilicate glass, a nitrogen-doped non-porous organosilicate glass,or a combination thereof. In one embodiment, the optional cap materiallayer 32 can be employed to provide a greater mechanical strength thanthe material of the dielectric material layer 30 during a subsequentplanarization process such as chemical mechanical planarization.Alternately or additionally, the optional cap material layer 32 can beemployed to protect the dielectric material layer 30 and structures tobe embedded therein from impurities that may diffuse down from upperlevels, and can function as a diffusion barrier layer that preventsvertical diffusion of metallic impurities, moisture, or other gaseousimpurities. The optional cap material layer 32 can be formed, forexample, by chemical vapor deposition (CVD) or atomic layer deposition(ALD). The thickness of the optional cap material layer 32 can be from 2nm to 30 nm, although lesser and greater thicknesses can also beemployed.

The optional hard mask layer 34 can include a dielectric material or aconductive metallic material. For example, the optional hard mask layer34 can include a dielectric material such as silicon oxide, siliconnitride, silicon oxynitride, a non-porous organosilicate glass, anitrogen-doped non-porous organosilicate glass, or a combinationthereof, or can include a conductive metallic material such as TiN, TaN,WN, TiC, TaC, WC, or a combination thereof. In one embodiment, theoptional hard mask layer 34 can be employed as a disposable ornon-disposable stopping layer during a subsequent planarization process.If the optional hard mask layer 34 is a non-disposable dielectricmaterial, the optional hard mask layer 34 can be employed to protect thedielectric material layer 30 and structures to be embedded therein fromimpurities that may diffuse down from upper levels, and can function asa diffusion barrier layer that prevents vertical diffusion of metallicimpurities, moisture, or other gaseous impurities. The optional hardmask layer 32 can include, for example, silicon nitride, siliconoxynitride, a nitrogen-doped organosilicate glass, or a combinationthereof. The optional hard mask layer 34 can be formed, for example, bychemical vapor deposition (CVD) or atomic layer deposition (ALD). Thethickness of the optional hard mask layer 34 can be from 2 nm to 30 nm,although lesser and greater thicknesses can also be employed.

The template layer 40 can include a dielectric material, a semiconductormaterial, and/or a conductive material. In embodiments in which aportion of the template layer 40 remains after formation of a pair ofconductive via structures, the template layer 40 includes a dielectricmaterial such as silicon oxide, silicon nitride, silicon oxynitride,porous or non-porous organosilicate glass, or a combination thereof.

In embodiment in which the entirety of the template layer 40 issubsequently removed during formation of a pair of conductive viastructures, for example, by planarization, the template layer 40 caninclude a dielectric material, a semiconductor material, and/or aconductive material. For example, the template layer 40 can include adielectric material such as silicon oxide, silicon nitride, siliconoxynitride, porous or non-porous organosilicate glass, or a combinationthereof, and/or a semiconductor material such as silicon, germanium, ora compound semiconductor material, and/or a conductive material such asTiN, TaN, WN, TiC, TaC, WC, Al, W, or a combination thereof.

The template layer 40 can be formed, for example, by chemical vapordeposition (CVD), physical vapor deposition (PVD), atomic layerdeposition (ALD), spin coating, or a combination thereof. The thicknessof the template layer 40 can be from 20 nm to 500 nm, although lesserand greater thicknesses can also be employed. In one embodiment, thetemplate layer 40 can include silicon oxide formed by chemical vapordeposition.

Each of the layers in the stack of the first organic planarization layer(OPL) 42, the first antireflective coating (ARC) layer 44, and the firstphotoresist layer 47 can be formed by spin coating. The first OPL 42includes a self-planarizing organic planarization material, which can bea polymer layer with sufficiently low viscosity so that the top surfaceof the first OPL 42 is a planar horizontal surface. The self-planarizingorganic planarization material can be any material employed for anorganic planarization layer in trilayer lithography methods known in theart. The thickness of the first OPL 42 can be from 10 nm to 200 nm,although lesser and greater thicknesses can also be employed.

The first ARC layer 44 is an optional layer, and can be formed, forexample, by spin coating. The first ARC layer 44 can include anyanti-reflective material known in the art, and can include siliconand/or an organic material. The thickness of the first ARC layer 44 canbe from 10 nm to 150 nm, although lesser and greater thicknesses canalso be employed.

The first photoresist layer 47 is applied directly on the first ARClayer 44 or directly on the first OPL 42, for example, by spin coating.The thickness of the first photoresist layer 47 can be from 200 nm to600 nm, although lesser and greater thicknesses can also be employed.The first photoresist layer 47 can be a layer of a photoresist sensitiveto deep-ultraviolet (DUV) radiation, extreme ultraviolet (EUV), ormid-ultraviolet (MUV) radiation as known in the art, or can be an e-beamresist that is sensitive to radiation of energetic electrons.

While the present disclosure is described employing the stack of thefirst OPL 42, the first ARC layer 44, and the first photoresist layer47, the stack of the first OPL 42, the first ARC layer 44, and the firstphotoresist layer 47 can be replaced with one or more layers thatinclude a photosensitive material as known in the art.

Referring to FIGS. 2A and 2B, the first photoresist layer 47 ispatterned with a first lithographic pattern by lithographic exposure anddevelopment. The first lithographic pattern includes a line portionhaving a first width w1 and referred to as a “primary line portion”herein. The first lithographic pattern can further include twoadditional line portions that are attached to the two ends of theprimary line portion and having a lengthwise direction that isperpendicular to the lengthwise direction of the primary line portion.The two additional line portions and the primary line portions can bemerged to form a single contiguous opening in the photoresist layerhaving an overall shaped of an “H.” Thus, the first lithographic patternincluding the primary line portion and two adjoined additional lineportions is herein referred to as an “H-shaped pattern.”

Referring to FIGS. 3A and 3B, the first lithographic pattern in thefirst photoresist layer 47 is transferred through the first ARC layer 44and the first OPL 42 by a pattern transfer etch, which can be ananisotropic etch. In one embodiment, the pattern transfer etch can be areactive ion etch that removes the materials of the first ARC layer 44and the first OPL 42 employing the first photoresist layer 47 as an etchmask.

After the top surface of the template layer 40 is physically exposedwithin an H-shaped opening in the stack of the first OPL 42, the firstARC layer 44, and the first photoresist layer 47, another anisotropicetch process is performed to form a contiguous line trench 51 having anH-shape in an upper portion of the template layer 40. The anisotropicetch process can include any chemistry that can etch the material of thetemplate layer 40 employing the first photoresist layer 47 as an etchmask. A primary portion of the contiguous line trench 51 underlying theprimary line portion of the H-shaped pattern in the first photoresistlayer 47 can have a width that is substantially the same as the firstwidth w1. The bottom surface of the contiguous line trench 51 may, ormay not, extend to the topmost surface of the at least one underlyingmaterial layer (30, 32, 34).

Referring to FIGS. 4A and 4B, the stack of the first photoresist layer47, the first ARC layer 44, and the first OPL 42 are removed, forexample, by ashing. A contiguous spacer layer 50 is formed within thecontiguous line trench 51 and over the top surface of the template layer40. The contiguous spacer layer 50 is formed as a single contiguouslayer without any hole therein. In an embodiment in which at least aportion of the template layer 40 remains after subsequent formation of apair of conductive via structures, the contiguous spacer layer 50includes a dielectric material such as doped silicon oxide, undopedsilicon oxide, silicon nitride, silicon oxynitride, organosilicate glass(OSG), or a combination thereof.

In an embodiment in which the entirety of the template layer 40 issubsequently removed after formation of a pair of conductive viastructures, the contiguous spacer layer 50 can include a dielectricmaterial, a semiconductor material, or a conductive material.

The material of the contiguous spacer layer 50 can be the same as, ordifferent from, the material of the template layer 40. The contiguousspacer layer 50 can be formed by a conformal deposition process or by anon-conformal deposition process provided that the sidewall stepcoverage is non-zero. In one embodiment, the contiguous spacer layer 50can be formed by a conformal deposition process such as low pressurechemical vapor deposition (LPCVD), and the thickness of the contiguousspacer layer 50 can be the same at all horizontal portions of thecontiguous spacer layer 50. Specifically, the contiguous spacer layer 50can have the same thickness in the recessed portion of the templatelayer 40 as in a non-recessed portion of the template layer 50, i.e.,above the topmost surface of the template layer 40 and above therecessed surface of the template layer 40 at the bottom of thecontiguous line trench 51.

The lateral thickness of vertical portions of the contiguous spacerlayer 50 within the recessed portions of the template layer 40 is lessthan one half of the first thickness w1 so that the contiguous linetrench 51 is not plugged by the contiguous spacer layer 50.

In one embodiment, the remaining portion of the contiguous line trench51 includes a trench portion having a width, which is herein referred toas a second width w2, that is less than the first width by twice thewidth of vertical portions of the contiguous spacer layer 50. In oneembodiment, the second width w2 can be less than a lithographicallyprintable dimension for deep ultraviolet lithography, i.e., asublithographic dimension for deep ultraviolet lithography, and thefirst width w1 can be a lithographic dimension for deep ultravioletlithography.

Referring to FIGS. 5A and 5B, an etch-resistant material layer 60L isdeposited by a conformal deposition method to fill the contiguous linetrench 51. The material of the etch-resistant material layer 60L isdifferent from the material of the contiguous spacer layer 50 and fromthe material of the template layer 40. Specifically, the material of theetch-resistant material layer 60L is more etch-resistant to a first etchchemistry to be subsequently employed to etch the contiguous spacerlayer 50, and is more etch-resistant to a second etch chemistry to besubsequently employed to etch the template layer 40.

In an embodiment in which at least a portion of the template layer 40remains after subsequent formation of a pair of conductive viastructures, the etch-resistant material layer 60L includes a dielectricmaterial. For example, the dielectric material of the etch-resistantmaterial layer 60L can be a dielectric metal oxide having a dielectricconstant greater than 8.0 and is known as a “high-k gate dielectricmaterial” in the art. The dielectric metal oxide can be formed, forexample, by chemical vapor deposition (CVD) or atomic layer deposition(ALD). Alternately, the contiguous spacer layer 50 and the templatelayer 40 can include organosilicate glass materials, and theetch-resistant material layer 60L can include silicon oxide, siliconnitride, silicon oxynitride, or a nitrogen-doped organosilicate glass.Yet alternately, the contiguous spacer layer 50 and the template layer40 can include an organosilicate glass material and/or silicon oxide,and the etch-resistant material layer 60L can include silicon nitride orsilicon oxynitride.

In an embodiment in which the entirety of the template layer 40 issubsequently removed after formation of a pair of conductive viastructures, the etch-resistant material layer 60L can include adielectric material or a conductive material. The dielectric materialthat can be employed for the template layer 40 includes a dielectricmetal oxide, silicon oxide, silicon nitride, silicon oxynitride, or anitrogen-doped organosilicate glass, or a combination thereof. Theconductive material that can be employed for the template layer 40includes a conductive metal nitride such as TiN, TaN, and WN, aconductive metal carbide such as TiC, TaC, WC, an elemental metal suchas Al, Cu, W, and combinations and stacks thereof. The conductivematerial for the template layer 40 can be deposited, for example, bychemical vapor deposition (CVD) or atomic layer deposition (ALD).

The thickness of the etch-resistant material layer 60L, as measuredabove the topmost surface of the contiguous spacer layer 50, is greaterthan ½ of the second width w2. The sum of the thickness of thecontiguous spacer layer 50 and the thickness of the etch-resistantmaterial layer 60L is greater than ½ of the first width w1.

Referring to FIG. 6A, the etch-resistant material layer 60L isvertically recessed employing the contiguous spacer layer 50 as an etchstop layer or as an end-point detection layer. Thus, the etch-resistantmaterial layer 60L is removed from above the topmost surface of thecontiguous spacer layer 50, while a remaining portion of theetch-resistant material layer 60L is present below the topmost surfaceof the contiguous spacer layer 50. The remaining portion of theetch-resistant material layer 60L has the second width w2, and is hereinreferred to as an etch-resistant material portion 60. The etch-resistantmaterial portion 60 is formed within the line trench and on sidewalls ofthe contiguous spacer layer 50. In one embodiment, the etch-resistantmaterial portion 60 can have a sub-lithographic lateral dimension fordeep ultraviolet lithography. The etch-resistant material portion 60 canhave an H-shaped horizontal cross-sectional shape between the plane ofthe topmost surface of the contiguous spacer layer 50 and the topsurface of the recessed portion of the contiguous spacer layer 50.

Referring to FIGS. 7A and 7B, a stack of a second organic planarizationlayer (OPL) 72, a second antireflective coating (ARC) layer 74, and asecond photoresist layer 77 is formed, for example, by spin coating. Thesecond OPL 72 can include the same type of material as the first OPL 72,and can have the same thickness range as the first OPL 42. The secondARC layer 74 can have the same type of material as the first ARC layer44, and can have the same thickness range as the first ARC layer 44. Thesecond photoresist layer 77 can have the same type of material as thefirst photoresist layer 47, and can have the same thickness range as thefirst photoresist layer 47.

While the present disclosure is described employing the stack of thesecond OPL 72, the second ARC layer 74, and the second photoresist layer77, the stack of the second OPL 72, the second ARC layer 74, and thesecond photoresist layer 77 can be replaced with one or more layers thatinclude a photosensitive material as known in the art.

Referring to FIGS. 8A and 8B, the stack of the second photoresist layer77, the second ARC layer 74, and the second OPL 72 is patterned with asecond pattern. Specifically, the second photoresist layer 77 ispatterned with the pattern, and the second pattern is transferredthrough the second ARC layer 74 and the second OPL 72 by a patterntransfer etch.

The second pattern includes an opening therein, and the opening in thesecond pattern straddles over a portion of the etch-resistant materialportion 60. In one embodiment, the etch-resistant material portion 60can be an H-shaped etch-resistant material portion including a primaryetch-resistant line portion having the second width w2 and a pair ofadjoining etch-resistant line portions that are adjoined to two ends ofthe primary etch-resistant line portion. In one embodiment, the openingin the second pattern can straddle over the primary etch-resistant lineportion. Additionally, sidewalls of the stack of the second photoresistlayer 77, the second ARC layer 74, and the second OPL 72 can overlieeach of the pair of adjoining etch-resistant line portions.

In one embodiment, the opening in the second pattern can have asubstantially rectangular shape, wherein a portion of the etch-resistantmaterial portion straddles over an area of a center portion of therectangular shape. A pair of parallel sides of the rectangle can overliethe pair of adjoining etch-resistant line portions, and another pair ofparallel sides of the rectangle can be laterally spaced by a regionincluding the entirety of the primary etch-resistant line portion.

Referring to FIGS. 9A and 9B, a composite pattern derived from thesecond pattern is transferred through the stack of the contiguous spacerlayer 50, the template layer 40, and optionally through the at least oneunderlying material layer (34, 32, 30) by an anisotropic etch thatemploys the combination of the second photoresist layer 77 and theetch-resistant material portion 60 as an etch mask. Because theetch-resistant material portion 60 prevents etching of materials locateddirectly underneath during the anisotropic etch, the composite patternformed by the anisotropic etch below the topmost surface of thecontiguous spacer layer 50 is a pattern of the intersection of thesecond pattern and the complement of the pattern of the etch-resistantmaterial portion 60.

The composite pattern includes a pair of via holes 79 laterally spacedby the etch-resistant material portion 60. In one embodiment, the pairof via holes 79 extends through the entirety of the template layer 40.The bottom surface of the pair of via holes 79 can protrude under thetop surface of the substrate layer 10, can be coplanar with the topsurface of the substrate layer 10, can be located between the bottommostsurface and the topmost surface of the at least one underlying materiallayer (34, 32, 30), or can be coplanar with the bottommost surface ofthe template layer 40.

Referring to FIGS. 10A and 10B, the stack of the second photoresistlayer 77, the second ARC layer 74, and the second OPL 72 are removed,for example, by ashing.

Referring to FIGS. 11A and 11B, a conductive material is deposited inthe pair of via holes 79 and over the topmost surface of the contiguousspacer layer 50, for example, by physical vapor deposition (PVD),chemical vapor deposition (CVD), electroplating, electroless plating, ora combination thereof. The conductive material can be, for example, Cu,TiN, TaN, WN, Ti, Ta, W, Al, or an alloy or a combination thereof.

Excess conductive material deposited above the topmost surface of thecontiguous spacer layer 50 and above the etch-resistant material portion60 is removed, for example, by chemical mechanical planarization (CMP)or a recess etch. Remaining portions of the conductive material withinthe pair of via holes 79 constitutes a pair of via structures 80.

The structure in FIGS. 11A and 11B includes a stack of the templatelayer 40 and the contiguous spacer layer 50; the etch-resistant materialportion 60 overlying a recessed portion of the stack; and the pair ofvia structures 80, embedded within the stack and laterally spaced by theetch-resistant material portion 60 and the recessed portion of the stack(40, 50). The entirety of the contiguous spacer layer 50 is contiguous,and the contiguous spacer layer 50 has the same thickness in therecessed portion of the stack (40, 50) as in the non-recessed portion ofthe stack (40, 50).

In one embodiment, the top surface of the contiguous spacer layer 50,the top surface of the etch-resistant material portion 60, and the topsurfaces of the pair of via structures 80 can be substantially coplanaramong one another. The etch-resistant material portion 60 can have anH-shaped pattern. The etch-resistant material portion 60 has arectangular portion, i.e., the primary etch-resistant line portionhaving the second width w2, that laterally contacts the pair of viastructures 80. The lateral extent of the pair of via structures 80 alongthe lengthwise direction of the primary etch-resistant material portionis bounded by a pair of parallel line portions within the H-shapedpattern, i.e., by the pair of adjoining etch-resistant line portions.The etch-resistant material portion 60 can have a sub-lithographiclateral dimension for deep ultraviolet lithography such as the secondwidth w2. Additionally, the width of each of the pair of adjoiningetch-resistant line portions can be a sub-lithographic lateral dimensionfor deep ultraviolet lithography.

In one embodiment, the etch-resistant material portion 60 can include adielectric material, and the pair of via structures 80 can beelectrically isolated from each other by the materials between the planeof the topmost surface of the pair of via structures 80 and the plane ofthe bottommost surface of the pair of via structures 80.

Various modifications to the structure of FIGS. 11A and 11B can bederived by eliminating any or all of the at least one underlyingmaterial layer (34, 32, 30) and/or by altering the height of the bottomsurfaces of the pair of via structures 80. Further, additionalmodifications to the structure of FIGS. 11A and 11B can be derived byfurther removing additional material from the topmost surface of thestructure of FIGS. 11A and 11B, for example, by chemical mechanicalplanarization. For example, a chemical mechanical planarization processcan proceed until a portion of the contiguous spacer layer 50 is removedwithout removing any of the template material layer 40, or can proceeduntil some of the template material layer 40 is removed without fullyremoving the etch-resistant material portion 60, or can proceed untilthe etch-resistant material portion 60 is fully removed with or withoutfurther removal of portions of the contiguous spacer layer 50 and thetemplate layer 40 between the bottommost surface of the etch-resistantmaterial portion 60 and the topmost surface of the at least oneunderlying material layer (34, 32, 30).

Referring to FIGS. 12A and 12B, a variation of the first exemplarystructure can be derived from the first exemplary structure of FIGS. 11Aand 11B by employing a semiconductor-on-insulator (SOI) substrate 8′including a handle substrate 10′, a buried insulator layer 12, and a topsemiconductor layer 30 instead of a semiconductor layer 10.

Referring to FIGS. 13A and 13B, a second exemplary structure can bederived from the first exemplary structure of FIGS. 11A and 11B byemploying a conductive material, such as TiN, TaN, WN, TIC, TaC, WC, Ta,Ti, W, Cu, Al, or an alloy or a combination thereof, for theetch-resistant material portion 60, and subsequently removing theetch-resistant material portion 60. The removal of the etch-resistantmaterial portion 60 can be effected by further planarizing the structureof FIGS. 11A and 11B so that the planarization stops at a height betweenthe height of the bottommost surface of the etch-resistant materialportion 60 and the height of the bottommost surface of the pair of viastructures 80. For example, the optional hard mask layer 34 can beemployed as the stopping layer for the planarization process.

Referring to FIGS. 14A and 14B, a third exemplary structure according toa third embodiment of the present disclosure can be derived from thefirst exemplary structure of FIGS. 1A and 1B by performing theprocessing steps of FIGS. 2A, 2B, 3A, and 3B with the modification ofthe first pattern. Specifically, the first pattern is modified toinclude a substantially rectangular opening having the first width w1.Thus, the H-shaped opening of the first embodiment is modified toinclude a rectangular opening without the adjoining line shapes.

Referring to FIGS. 15A and 15B, the processing steps of FIGS. 4A and 4Bare performed as in the first embodiment. A rectangular line trench isformed in the template layer 40 such that the lengthwise direction ofthe rectangular line trench is the same as the lengthwise direction ofthe rectangular opening in the first photoresist layer 47.

Referring to FIGS. 16A and 16B, the processing steps of FIGS. 5A and 5Bare performed as in the first embodiment.

Referring to FIGS. 17A and 17B, the processing steps of FIGS. 6A and 6Bare performed as in the first embodiment.

Referring to FIGS. 18A and 18B, the processing steps of FIGS. 7A and 7Bare performed as in the first embodiment.

Referring to FIGS. 19A and 19B, the processing steps of FIGS. 8A and 8Bare performed as in the first embodiment. The etch-resistant materialportion 60 of the third embodiment consists of a rectangular lineportion and does not include any adjoining line portions that arepresent in the H-shaped etch-resistant material portion 60 of the firstembodiment. In one embodiment, the second opening can have a rectangularshape. A pair of sides of the rectangle is laterally spaced by a regionincluding a center portion of the etch-resistant material portion 60.End portions of the etch-resistant material portion 60 are locatedoutside the area of the rectangle, and are thus covered by the secondphotoresist 77.

Referring to FIGS. 20A and 20B, the processing steps of FIGS. 9A and 9Bare performed as in the first embodiment. Because the etch-resistantmaterial portion 60 of the third embodiment is not H-shaped, the lateralextent of the pair of via holes 79 of the third embodiment is notbounded in the lengthwise direction of the etch-resistant materialportion 60 by any portion of the etch-resistant material portion 60. Thespacing between the pair of the via holes 79 is the same as the width ofthe etch-resistant material portion 60, i.e., the second width w2.

Referring to FIGS. 21A and 21B, the processing steps of FIGS. 10A and10B are performed as in the first embodiment.

Referring to FIGS. 22A and 22B, the processing steps of FIGS. 11A and11B are performed as in the first embodiment. The etch-resistantmaterial portion 60 has a rectangular shape, and the pair of viastructures 80 is separated along a widthwise direction of therectangular shape. The etch-resistant material portion can have asub-lithographic lateral dimension for deep ultraviolet lithography suchas the second width w2.

Referring to FIGS. 23A and 23B, a variation of the third exemplarystructure can be derived from the third exemplary structure employingthe same methods as in the variation of the first exemplary structureillustrated in FIGS. 12A and 12B.

Referring to FIGS. 24A and 24B, a fourth exemplary structure accordingto a second embodiment of the present disclosure can be derived from thethird exemplary structure employing the same methods as the secondembodiment. The fourth exemplary structure can have the same features asthe second exemplary structure of FIGS. 13A and 13B.

While the disclosure has been described in terms of specificembodiments, it is evident in view of the foregoing description thatnumerous alternatives, modifications and variations will be apparent tothose skilled in the art. Each of the various embodiments of the presentdisclosure can be implemented alone, or in combination with any otherembodiments of the present disclosure unless expressly disclosedotherwise or otherwise impossible as would be known to one of ordinaryskill in the art. Accordingly, the disclosure is intended to encompassall such alternatives, modifications and variations which fall withinthe scope and spirit of the disclosure and the following claims.

What is claimed is:
 1. A method of forming a patterned structurecomprising: forming a line trench having a first pattern in an upperportion of a template layer; forming a contiguous spacer layer onsidewalls and a bottom of said line trench and over a top surface ofsaid template layer, wherein said contiguous spacer layer is a singlelayer composed of a single first material; forming an etch-resistantmaterial portion on a portion of said contiguous spacer layer that islocated within said line trench to completely fill said line trench,wherein said etch-resistance material portion has a top surface coplanarwith a topmost surface of said contiguous spacer layer located abovesaid top surface of said template layer, wherein said etch-resistantmaterial portion is composed of a single second material different fromsaid first material; forming a patterned layer over portions ofhorizontal portions of said contiguous spacer layer, said patternedlayer comprising a third material different from said second material ofsaid etch-resistant material portion and having a second patternincluding an opening therein, wherein said opening straddles over saidetch-resistant material portion and exposes said etch-resistant materialportion and remaining portions of said horizontal portions of saidcontiguous spacer layer; and transferring a composite pattern of anintersection of said second pattern and a complement of a pattern ofsaid etch-resistant material portion into said template layer using acombination of said patterned layer and said etch-resistant materialportion as an etch mask.
 2. The method of claim 1, wherein saidcomposite pattern comprises a pair of via holes laterally spaced by saidetch-resistant material portion.
 3. The method of claim 1, wherein saidline trench is formed by: forming a stack comprising at least saidtemplate layer and a first photoresist layer on a substrate; formingsaid first pattern in said first photoresist layer; and transferringsaid first pattern into said upper portion of said template layer toform said line trench.
 4. The method of claim 3, further comprising:forming a second photoresist layer over said etch-resistant materialportion and horizontal portions of said contiguous spacer layer; andpatterning said second photoresist layer with said second pattern,wherein said patterned layer comprises said patterned second photoresistlayer.
 5. The method of claim 1, wherein said etch-resistant materialportion is formed by: forming an etch-resistant material layer in saidline trench and over said contiguous spacer layer, wherein saidetch-resistant material layer is a single layer composed of said singlesecond material; and removing said etch-resistant material layer fromabove said topmost surface of said contiguous spacer layer, wherein aremaining portion of said etch-resistant material layer constitutes saidetch-resistant material portion.
 6. The method of claim 1, wherein saidetch-resistant material portion comprises a dielectric metal oxide. 7.The method of claim 1, wherein a pair of via holes extending throughsaid template layer is formed upon transfer of said composite patterninto said template layer, wherein said etch-resistant material portionis present over a portion of said template layer after formation of saidpair of via holes.
 8. The method of claim 7, further comprising: fillingsaid pair of via holes with a conductive material; and removing aportion of said conductive material from above said etch-resistantmaterial portion and said contiguous spacer layer, wherein a pair of viastructures are formed within said pair of via holes.
 9. The method ofclaim 8, wherein said opening has a substantially rectangular shape,wherein a portion of said etch-resistant material portion straddles overan area of a center portion of said rectangular shape.
 10. The method ofclaim 1, wherein said first pattern is an H-shaped pattern.
 11. Themethod of claim 1, wherein said first pattern has a rectangular opening,wherein a lengthwise direction of said rectangular opening is alengthwise direction of said line trench.
 12. The method of claim 7,further comprising: forming at least one underlying material layer on asubstrate, wherein said template layer is formed on top of said at leastone underlying material layer, and said pair of via holes extend throughat least an upper portion of said at least one underlying materiallayer; filling said pair of via holes with a conductive material; andremoving portions of said conductive material from above one of said atleast one underlying material layer, wherein remaining portions of saidconductive material constitute a pair of via structures.
 13. The methodof claim 1, wherein vertical portions of said contiguous spacer layer donot completely fill said line trench.